A fleet of jet-powered catamarans has opened the British capital's last uncrowded thoroughfare - the River Thames - to commuter traffic.

"There's nothing else like this: an intensive river shuttle service in the center of London," said Roger Mabbott, deputy managing director of Thames Line PLC.Since the service's debut June 1, the firm's three boats have cruised past cars on choked streets to ferry about 600 passengers a day from central London to the booming Docklands area.

The catamarans - twin-hulled boats that can reach speeds of about 28 mph - carry up to 62 passengers and are powered by two turbo-charged Volvo jet engines.

One leaves Charing Cross Pier in London's West End every 15 minutes from 7 a.m. to 10 p.m. for a five-mile journey to the Isle of Dogs, heart of the sprawling Docklands redevelopment area, where decrepit warehouses are being turned into modern residential and light industry complexes.

The full trip with two stops takes 20 minutes. A similar journey on the London Underground subway takes up to 30 minutes, London Regional Transport spokesmen said.

One big difference is the price. The subway trip costs 80 pence, or $1.36, each way. The catamaran ride costs 4 pounds, or $7.20, each way.

"There's an element to competing with all forms of transport," Mabbott said, "but what we're looking to provide is service to places the Underground, buses and cars don't get to easily."

Traditional ferries have not operated with the speed or frequency of the Thames Line catamarans, Mabbott said.

Thames Line PLC was established with $8.1 million in 1986 to simultaneously develop property in the Docklands and create a river shuttle for the growing number of people living and working there.

Mabbott said Thames Line's operating costs for June broke even at $108,600 to $126,700, with the boats carrying an average of five passengers per trip.

He expects 80 percent of the passengers to be commuters or business people with an interest in the Docklands, and 20 percent tourists.

Passengers last week gave Thames Line generally favorable reviews, but one said some problems still need working out.